Moscow, ID Frost Dates
Average frost dates, USDA hardiness zone, and growing season length for Moscow, Idaho.
Gardening in Moscow
University of Idaho's Palouse country college town sits on some of the most fertile wheat-growing soil in the world — rolling loess hills that grow food beautifully.
Zone 5b with 138 frost-free days. The Palouse hills' wind-deposited loess soil is deep and naturally fertile. The climate is cooler and moister than southern Idaho.
UI's agricultural programs serve Idaho's farming community. The Palouse's famous rolling hills of wheat extend to backyard gardens that benefit from the same extraordinary soil.
What This Means for Moscow Gardeners
The average last spring frost in Moscow is around May 10, and the average first fall frost arrives around September 25. That gives you approximately 138 frost-free days to work with.
138 frost-free days means every warm day counts. Focus on cold-hardy crops that thrive in your moderate temperatures: kale, lettuce, peas, radishes, potatoes, and root vegetables. For warm-season crops, choose only the shortest-season varieties (sub-65-day tomatoes, 55-day beans) and start everything indoors. Season extension — row covers, cold frames, plastic mulch — isn't a luxury here, it's essential infrastructure.
These dates are based on NOAA 30-year Climate Normal data for the Moscow area. Your actual frost dates could shift 2-3 weeks in either direction in any given year. Learn more about our data sources.
What to Grow in Moscow
With 138 frost-free days, Moscow gardeners need to plan strategically — start warm-season crops indoors and choose short-season varieties. Cool-season crops are your strength, thriving in the moderate temperatures that define your growing window. Recommended starting points: kale, lettuce, peas, carrots, potatoes, radishes, garlic, and short-season tomatoes.
See the full Idaho planting guide for all 40 plants: Idaho Planting Calendar. Or enter your zip code for exact planting dates personalized to Moscow.
More About Zone 5B
Moscow is in USDA Hardiness Zone 5B, which means average annual extreme minimum temperatures between -15°F to -10°F. View the full Zone 5B planting guide.
See the complete planting calendar for Idaho: Idaho Planting Calendar.
Other Cities in Idaho
Frequently Asked Questions
These dates are based on NOAA's 30-year Climate Normal data for the Moscow area. They represent historical averages, not predictions. In any given year, the actual last frost could be 2-3 weeks earlier or later. Microclimates within Moscow (urban heat islands, hilltops, low-lying valleys) can also shift your local frost dates by a week or more.
Start everything possible indoors — your 138-day season doesn't leave room for a slow start. Direct sow only the fastest, hardiest crops (radishes, lettuce, peas) 3-4 weeks before last frost (May 10). Choose short-season varieties for warm crops. Enter your zip code for exact dates.